1. Field of the Invention
The present invention belongs to a technical field of widening a viewing angle of a polarizing plate, concretely relating to a wide-view polarizing plate and a liquid-crystal display device employing it.
2. Related Art
A transmissive liquid-crystal display device generally comprises a pair of polarizing plates disposed with their polarization axes kept perpendicular to each other. However, even when the two polarizing plates are so disposed that their polarization axes could cross perpendicularly to each other, they may be still shifted from perpendicular crossing configuration relative to the incident light running in oblique directions. This is one reason for light leakage in oblique directions in the black state of liquid-crystal display devices. Accordingly, for providing a liquid-crystal display device having excellent viewing angle characteristics, it is important to solve a problem of viewing angle dependence of polarizing plate. Heretofore, for wide-view polarizing plates, various proposals have been made for combining a polarizing element and a retardation layer having predetermined optical characteristics (for example, JP-A No. 2001-350022). Also proposed is use of a polarizing element of which the refractive index in the transmission axis direction falls within a predetermined range (JP-A No. H10-268294). Further, as a polarizing plate having wide-view characteristics, proposed is a laminate polarizing plate constructed by combining a polarizing element with the light absorption axis in the pale of the plate and a polarizing element with the light absorption axis in the thickness direction of the plate (for example, JP-A 2001-242320 and JP-T 2006-503325).